Boss DD-8 Reference Manual page 6

Connections
AC Adaptor
(PSA series; sold
separately)
Guitar Amplifier
You can obtain a variety of different delay effects by changing how the connections are made.
6
For more information, refer to "Setting the Output Method" (p. 15).
Keyboard
Electric Guitar
Footswitch
(FS-6 etc.)
Expression Pedal
(Roland EV-5 etc.)